With the increase of the wafer diameter and the decrease of the critical dimension, the surface cleanliness of the wafer becomes more demanding. Currently, the cleaning apparatus achieves the cleaning effects through spraying cleaning solutions to the surface of the high speed rotating wafer. However, during the high speed rotation of the wafer, the cleaning solution will be flung off the wafer surface and collide with a surrounding process chamber wall under the centrifugal force, then backsplash may occur, which may result in the cleaning solution being returned to the wafer surface and contaminating the wafer. Such contamination will degrade the cleaning process performance. Prior art attempts to prevent such contamination by increasing the structural complexity of the process chamber through providing additional components in the process chamber. However, it becomes difficult to perform the subsequent cleaning processes in the process chamber.